1. Field of the Invention
The present invention relates to an anti-reflection film forming material for forming an anti-reflection film to be provided on a resist film, and a method for forming a resist pattern using the anti-reflection film forming material.
2. Related Art
Semiconductor wiring substrates are generally formed by laminating a dielectric layer (insulation layer) on a silicon wafer, or the like. A patterned conductive layer (i.e., a wiring layer) is then formed in the dielectric layer to form a semiconductor wiring structure.
The formation of the wiring layer is carried out as follows. First, a conductive layer is formed on a dielectric layer uniformly, and a resist film is formed on this conductive layer. A resist pattern is formed by irradiation (exposure) of a patterning light on this resist film, followed by development, and a wiring layer is formed by patterning of the conductive layer with an etching process using the resist pattern as a mask. Then, after removing the resist film completely, a dielectric layer is further laminated on the conductive layer to configure a wiring layer in the dielectric layer.
It has been conventionally known that a problem referred to as a stationary wave effect due to multiple interference occurs when a pattern is formed by exposing a resist film in the step of forming a wiring layer. That is, an exposed light is transmitted through the resist film, and the transmitted light is reflected on an underlayer surface and a part of the reflected light is further reflected on an upper surface of the resist film, with such event being repeated in the resist film. The interference of an irradiated light at a single wavelength, which has entered the resist film formed on the substrate, with the reflected light from the substrate, and variation of light energy amounts absorbed in a thickness direction of the resist film is generated. This variation affects a size width of the resist pattern obtained after development, resulting in reduction of the dimensional accuracy of the resist pattern.
This reduction in the dimensional accuracy of the resist pattern is of significant concern, particularly when a fine pattern is formed on a substrate having varying levels because the thickness of the resist film becomes inevitably different at the relief structures in portions having such varying levels. Thus, it has been desired to develop a technology in which the above interference effect is eliminated and the dimensional accuracy of the resist pattern is not reduced even in the case of fine patterns formed on a substrate having varying levels.
Consequently, a method in which an anti-reflection film having a property of absorbing the exposed light is formed before forming a resist film on a substrate and a resist film is formed on the anti-reflection film (for example, Patent Document 1, etc.); and a method in which an anti-reflection film constituted with polysiloxane, polyvinyl alcohol or the like is formed on a resist film provided on a substrate (for example, Patent Documents 2 and 3, etc.) have been employed conventionally.
Patent Document 1: U.S. Pat. No. 4,910,122.
Patent Document 2: Japanese Examined Patent Application, Publication No. H4-55323.
Patent Document 3: Japanese Unexamined Patent Application, Publication No. H3-222409.